From: Sanyam Kumat <124618873+sanyamk23@users.noreply.github.com>
Date: Sat, 6 Jun 2026 21:38:15 +0000 (+0530)
Subject: gh-148954: Escape methodname in xmlrpc.client.dumps() to prevent XML injection (GH... 
X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=ab930175e7e909aaa3ec7e761bfdbb886677bebb;p=thirdparty%2FPython%2Fcpython.git

gh-148954: Escape methodname in xmlrpc.client.dumps() to prevent XML injection (GH-148968)
---

diff --git a/Lib/test/test_xmlrpc.py b/Lib/test/test_xmlrpc.py
index 2803c6d45c27..ee0e24f6e86a 100644
--- a/Lib/test/test_xmlrpc.py
+++ b/Lib/test/test_xmlrpc.py
@@ -208,6 +208,17 @@ class XMLRPCTestCase(unittest.TestCase):
         self.assertEqual(xmlrpclib.loads(strg)[0][0], value)
         self.assertEqual(xmlrpclib.loads(strg)[1], methodname)
 
+    def test_dump_escape_methodname(self):
+        payload = 'foo</methodName><injected attr="evil"/><methodName>bar'
+        s = xmlrpclib.dumps((), methodname=payload)
+        self.assertIn(
+            '<methodName>foo&lt;/methodName&gt;&lt;injected attr="evil"/&gt;'
+            '&lt;methodName&gt;bar</methodName>', s
+        )
+        self.assertNotIn('<injected attr="evil"/>', s)
+        load, m = xmlrpclib.loads(s)
+        self.assertEqual(m, payload)
+
     def test_dump_bytes(self):
         sample = b"my dog has fleas"
         self.assertEqual(sample, xmlrpclib.Binary(sample))
diff --git a/Lib/xmlrpc/client.py b/Lib/xmlrpc/client.py
index f441376d09c4..84e4e4d11a73 100644
--- a/Lib/xmlrpc/client.py
+++ b/Lib/xmlrpc/client.py
@@ -965,7 +965,7 @@ def dumps(params, methodname=None, methodresponse=None, encoding=None,
         data = (
             xmlheader,
             "<methodCall>\n"
-            "<methodName>", methodname, "</methodName>\n",
+            "<methodName>", escape(methodname), "</methodName>\n",
             data,
             "</methodCall>\n"
             )
diff --git a/Misc/NEWS.d/next/Library/2026-04-24-19-54-00.gh-issue-148954.v1.rst b/Misc/NEWS.d/next/Library/2026-04-24-19-54-00.gh-issue-148954.v1.rst
new file mode 100644
index 000000000000..6245af7e362e
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-04-24-19-54-00.gh-issue-148954.v1.rst
@@ -0,0 +1 @@
+Fix XML injection vulnerability in :func:`xmlrpc.client.dumps` where the ``methodname`` was not being escaped before interpolation into the XML body.